1. Field
The present disclosure relates to a printer driven by a battery.
2. Description of the Related Art
Printers operating by using a battery have been already proposed so that a user can casually use printers, for example. In this case, repetition of production of printed objects and repetition of discharge of a battery gradually exhaust the battery. Whether the battery has exhausted or not can be determined by setting a predetermined threshold value, for example, and by checking if an output voltage value of the battery changing over time has lowered to the threshold value or not.
Here, there is a case where a plurality of types of batteries is appropriately replaced and used in one and the same printer. In that case, nominal voltages, voltage drop characteristics at the beginning of use, voltage drop characteristics when the battery is exhausted after the use was started, and the like might be different according to the type of the batteries. For example, if a case in which an alkali manganese battery which is a primary battery is used is compared with a case in which a nickel hydrogen battery which is a secondary battery is used, the nominal voltage of the alkali manganese battery is higher than that of the nickel hydrogen battery, while a voltage drop amount of the alkali manganese battery when print load is applied is larger than that of the nickel hydrogen battery. As a result, the voltage while the print load is applied during exhaustion (hereinafter referred to as a “print load voltage” as appropriate) of the alkali manganese battery is likely to be lower than that of the nickel hydrogen battery. Moreover, when use is continued and exhaustion progresses, the above described print load voltage of alkali manganese battery lowers to a limit value in use (so-called lower limit voltage) relatively early, while the print load voltage of nickel hydrogen battery lowers to the above described lower limit voltage relatively slow.
Therefore, when the above described threshold value used for exhaustion determination is set uniformly in accordance with the lower limit voltage on the use of the alkali manganese battery, for example, if the nickel hydrogen battery is actually used, the voltage falls under a recommended final voltage of the nickel hydrogen battery, which may cause an over discharge state in some cases to give a bad influence to the battery. On the contrary, when the above described threshold value is set uniformly in accordance with a recommended final voltage of the nickel hydrogen battery, if the alkali manganese battery is actually used, determination of exhaustion is made although the voltage has not reached the lower limit voltage of the alkali manganese battery and exhaustion has not progressed so much, and an operator cannot use up the battery until sufficient discharge has been made.
As a prior art giving consideration to the use of the plurality of types of batteries as described above is known. In this prior art, a battery voltage is detected in both a state in which power is not supplied from a battery to a print head, a motor or the like and no load is applied and a state in which power is supplied from the battery to the print head, the motor and the like and a load is applied. Then, the lower limit voltage of a battery attached at that time is determined on the basis of a voltage drop amount in those two states.
However, in the above described prior art, a voltage drop amount is calculated by using only two voltage values, that is, an output voltage value of the battery in a no-load state and an output voltage value of the battery in a load-applied state, the type of the battery (primary battery or secondary battery or the like) is automatically detected by this voltage drop amount, and an exhausted state of the battery is determined by using separate threshold values each corresponding to the detected type of the battery. In this case, if the type of the battery is falsely detected, an inappropriate threshold value is set, and as a result, there is a problem that a degree of exhaustion of the battery cannot be determined with high accuracy.
In order to avoid the above described situation, a method can be considered in which a battery type is manually input by an operator, for example, so that the above described exhaustion determination is made reliably in accordance with the input battery type. However, in this case, the input operation by the operator is needed at each time of use, which is troublesome, and there may be a possibility that the operator erroneously inputs a type different from an actual battery type.